Kodak D-31 manual Water Protection, Effects of High and Low Relative Humidities, High Humidity

Water Protection

Film records should be protected from possible water damage, such as from leaks, fire-sprinkler discharge, and flooding. If possible, storage facilities should be located above basement levels. Storage cabinets should be raised so that the lowest shelf or drawer is at least 15.2 cm (6 in.) off the floor and should be constructed so that water cannot splash through ventilating louvers onto the records. Drains provided should have adequate capacity to keep water from a sprinkler discharge from reaching a depth of 7.6 cm (3 in.).

If the record-storage area should become flooded, prompt steps should be taken to reclaim any immersed records. Allowing microfilm records

to dry, even partially, will cause the layers to stick together. If there are no local facilities for rewashing and drying the films immediately, promptly place the films in a water-filled container and send them to a laboratory where they can be washed and dried properly.10

Effects of High and Low

Relative Humidities

The choice of humidity level for storage depends on the type of photographic film and the humidity of the work area. In order to minimize subsequent moisture conditioning in storage, the humidity of the work area should not be markedly different from that of the storage area. Very large humidity differences may lead to some physical distortion. The best relative humidity for storage is the lowest that can be achieved practically and controlled reliably, within the limits specified

in ANSI/PIMA IT9.11-1998 and ISO 189115 or their latest revisions.

High Humidity

Storage in moist air, such as that frequently found in basement rooms, and storage humidities above 50% should be avoided; relative humidities of 40% or less are recommended for minimizing the possibility of growth of microscopic blemishes. At humidities above 60%, there is the additional danger of fungus growth.

These curves show the relationship between relative humidity and the moisture content of a typical emulsion, triacetate film base, Estar Base, and a complete film at equilibrium of various relative humidities at 21°C (70°F).

Low Humidity

At low humidities, problems of brittleness or static might arise if the films are to be handled frequently. However, in the case of inactive films (regardless of their intended permanence), the increased protection that low humidity gives against microscopic blemishes might be desirable. The recommended humidity is

30% for silver-gelatin polyester-base film and 15% for silver-gelatin acetate-base film and all other silver and non-silver films.5

D-31 June 2002 5